The present invention relates to a mechanism for detecting the end of an ink ribbon. More particularly, the invention relates to a mechanism for mechanically detecting when the end of a cassette-contained ink ribbon is reached in a serial printing device.
In conventional mechanisms for detecting the end of the ink ribbon which is being used in a serial printer, typewriter, or the like, a transparent or reflective tape leader is fastened at the end of the ink ribbon to signal the approach of the end. Then, when the useful part of the tape has passed an optical sensor, the approach of the end is detected by utilizing the optical transparency or reflectivity of the leader tape.
However, serial printers and the like are required to be portable, compact and low in cost. Such devices use a power source of limited electric energy. Accordingly, it is not desirable to utilize an optical sensor which must be continuously supplied with electricity since the necessary power source is heavy, bulky, and expensive.